Multiple position electrical switch with contact rails and dummy contact pressure stabilizers



Dec. 14, 1965 c, HOY .ETAL 3,223,794

MULTIPLE POSITION ELECTRICAL SWITCH WITH CONTACT RAILS AND DUMMY CONTACT PRESSURE STABILIZERS Filed Nov. 13, 1963 2 Sheets-Sheet 1 Dec. 14, 1965 OY ETAL 23,794

L. c. H MULTIPLE POSITION ELECTRICAL SWITCH WITH CONTACT RAILS AND DUMMY CONTACT PRESSURE STABILIZERS Filed Nov. 13, 1963 2 Sheets-Sheet 2 1%: 6 Era 10 l.- clzdch $01. 2,; 34 2 704 7 All Cblldil" 723 $1 56 729 Q 112 v F 44 INVENTORS Leland C Ho B0135 Ha ck Patented Dec. 14, 1965 3,223,794 MULTIPLE POSHTION ELECTRICAL SWITCH WITH CONTACT RAILS AND DUMMY CONTACT PRESSURE STAItILIZEItS Leiand C. Hey, Siroirie, and Borys Hazek, Mount Prospect,

IlL, assignors to Indalr Manufacturing Corp., Northlhrooi: Ill, a corporation of Illinois Filed Nov. 13, 1963, Ser. No. 323,447 15 Claims. (Cl. 200-16) This invention relates to electrical switches which may have a fairly large number of positions, such as four or five, for controlling a correspondingly large number of functions.

One object of the present invention is to provide new and improved electrical switches which are particularly well adapted for controlling the supply of electrical power to several different circuits.

Thus, a further and more specific object is to provide new and improved switches which are well adapted for use in an air conditioning system for automobiles, the system being such that the switch is called upon to control the operation of a compressor, and the operation and speed of a blower motor.

Another object is to provide a new and improved switch vfor supplying power to a plurality of circuits, the switch having an off position in which none of the circuits are energized, and a plurality of on positions in which various circuits are individually energized, the switch being constructed and arranged so as to energize one of the circuits in all of the on positions.

A further object is to provide a new and improved switch which is provided with a movable contactor having a first portion adapted to form a bridge between stationary elongated contact bars, and second and third portions adapted to engage a series of stationary contact points adjacent the contact bars.

A further object is to provide a new and improved switch of the foregoing character in which the three portions of the contactor are arranged in the form of a triangle, and in which the fixed elements of the switch are arranged to equalize the contact pressure among the three portions of the contactor, in all positions of the switch.

A still further object is to provide a new and improved switch of the foregoing character in which semiperforations or fixed dummy contacts are provided to engage portions of the contactor in certain positions of the switch so as to insure equalization of the contact pressure.

Another object is to provide such a new and improved switch which is versatile and dependable, yet highly economical in construction.

Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings and in which:

FIGS. 1, 2 and 3 are front, side and rear elevational views of an electrical switch to be described as an illustrative embodiment of the present invention.

FIG.4 is an exploded or disassembled perspective view of the switch of FIGS. 1-3.

FIG. 5 is a sectional view, taken generally along the line 55 in FIG. 3.

FIG. 6 is a somewhat diagrammatic view showing the contact plate and a typical circuit for the switch, the view also showing the movable contactor in phantom to illustrate the operation of the switch.

FIG. 7 is a cross sectional view taken generally along the line 7-7 in FIG. 2.

FIG. 8 is a side elevational view of a modified switch.

FIG. 9 is an enlarged rear view of the switch of FIG. 8 with the contact plate removed, the view being taken generally as indicated by the line 99 in FIG. 8.

FIG. 10 is a view similar to FIG. 6 but showing the modified switch of FIGS. 8 and 9.

As already indicated, FIGS. 17 illustrate an electrical switch in having a casing or housing 22 which may be made of metal or other suitable material. The rear side of the illustrated casing 22 is closed by a terminal member or plate 24, which may be made of plastic or other insulating material.

The illustrated casing 22 has a front wall of side walls 28 and 29, and a pair of end walls 30 and 31. The side and end walls 28-31 extend rearwardly from the front wall 26.

The insulating terminal plate 24 may be suitably secured to the open rear side of the casing 22. In this case, the casing 22 is formed with rearwardly projecting tabs or ears 32, 33 and 34 which are bent inwardly behind the terminal plate 24. It will be seen that the edges of the terminal plate 24 are formed with slots or notches 3a, 37 and 38 for receiving the ears 32-34.

The switch 20 is provided with an operating member in the form of a lever 40 which is swingably mounted on a bracket 42 secured to the front wall 26 of the casing 22. A rivet or other fastener 44 provides a pivot between the lever 40 and the bracket 42. It will be seen that the lever 40 has an inner arm 46 which extends into the casing 22 through a slot or opening 48 in the front wall 26 thereof. A slot 50 may be formed in the bracket 42, in alignment with the slot 48. The lever 49 has an outer arm 52 whereby the switch 20 may be operated, either manually or automatically.

Within the casing 22, the illustrated switch 20 is provided with a movable carriage 56 which preferably is made of plastic or other insulating material. A conductive contactor 58 may be mounted on the carriage 56 so as to be movable therewith. The contactor 58 may be made of copper or other suitable metal.

It will be seen that the contact plate 24 supports a plurality of contact members or elements, which will be described in detail presently. A spring 6% is provided between the insulating carriage 56 and the contactor 58 to bias the contactor rearwardly against the contact members on the insulating contact plate 24. At the same time, the spring 61 biases the carriage 56 forwardly against the front wall 26 of the casing 22. In this case, the spring 66 is of the compression type and is in the form of coiled wire. An annular seat 62 may be formed in the rear side of the carriage 56 to receive and locate the spring 6%.

The inner arm 46 of the lever 40 is connected to the carriage 56 in such a manner that the swinging movement of the lever will cause the carriage 56 to slide longitudinally within the casing 22. The side walls 28 and 29 confine the carriage 56 and serve as guides for such longitudinal movement of the carriage. As shown, the carriage 56 is formed with a slot or socket 64 for receiving the inner arm 46 of the lever 40. 46 has an enlarged and rounded end portion 66 which is adapted to slide and rock within the slot 64.

The contractor 58 is retained and guided on the carriage 56 by means of a pair of flanges or tabs 70 and 71 which project forwardly from the contractor, generally at right angles thereto. Slots or notches 72 and 73 are formed in the upper and lower sides of the carriage 56 for slidably receiving the flanges 7 0 and 71.

A detenting action may be provided between the carriage 56 and the casing 22 so that the carriage will be detained in each of its operating positions. As shown, the carriage 56 is provided with a plurality of rounded detent projections 76 which extend forwardly therefrom. The illustrated carriage 56 has four such detent projections, located at the four front corners of the carriage 26, a pair 56 which is generally rectangular in shape. Alternate detent projections 78 and grooves 80 are formed in the front wall 26 of the casing 22. In this case, the detent projections '78 and grooves 88 are sufiiciently numerous to detain the carriage 56 in live ditferent operating positions. The detent projections '78 may be stamped or otherwise formed rearwardly from the front wall 26. The detent projections '78 and grooves 88 are so located on the front wall 26 of the casing 22 that the detent projections '76 on the carriage 56 must pass over the projections '78 and across the grooves 89 as the carriage 56 is moved longitudinally within the casing 22. The spring 68 exerts a forward biasing force on the carriage 56 so that the detent projections '75 are detained in the successive detent grooves or recesses 88.

As already mentioned, the illustrated switch 20 has five different operating positions, which are designated OFF, AC, LOW, MEDIUM and HIGH in FIG. 5. The switch is particularly well adapted for use in connection with an air conditioning system for automobiles. Thus, the initials AC stand for air conditioner, while the terms low, medium and high refer to the various speeds of the blower employed in connection with the air conditioner. Of course, the switch is applicable to many other types of service.

It now will be in order to describe the details of the contactor S8, and the various contact members on the insulating contact plate 24. The contactor and the various contact members are constructed and arranged so that various circuits may be established or energized in the different positions of the switch.

In the illustrated switch construction, there is one contact member 84 which is in contact with the contactor 58 in all of the operating positions of the switch 20. As shown, the contact member 84 is in the form of an elongated bar or rail which extends parallel to the direction of movement of the contactor 58. The illustrated rail 84 is cylindrically curved in cross section and is generally in the form of a half cylinder, as shown to advantage in FIG. 7.

The second rail or bar 86 is formed parallel to and adjacent one end portion of the rail 84. The rail 86 is also generally in the form of a half cylinder. The two rails 84 and 86 provide a groove or trough 88 therebetween. This groove or trough 88 is adapted to receive and guide the contact point 90 which is formed on the contactor 58. Preferably, the contact point 90 is hemispherical in form. The illustrated contactor 58 is generally in the form of a plate or body 92 made of sheet copper or other metal. The contact point 98 is stamped or otherwise formed rearwardly from the plate 92. It will be seen that the contact point 91 is located near the upper end of the plate 92, which is generally rectangular in shape. The contact point 98 is adapted to slide along the parallel bars or rails 84 and 86. One side portion of the contact point 90 engages the rail 84 in all of the positions of the switch. However, the contact point 90 engages the rail 86 in the off position only.

In the illustrated construction, the rails 84- and 86 are formed integrally, from a single piece of sheet copper or other metal. Thus the rails 84 and 86 are connected together both electrically and mechanically. It will be seen that a tab or lug 94 extends laterally from one side of the rail 86. The tab 9 may be secured against the insulating terminal plate 24 by means of a rivet 96.

Means may also be provided to prevent the rails 84 and 86 from being swung along the contact plate 24, about the rivet 96. In this case, as shown, the rail 84 is formed with a tab or car 98 which is received in a hole or recess 108 in the insulating plate 24.

The illustrated switch 28 is provided with another bar or rail 102 which is engaged by the contactor 58 in all of the positions of the switch except the oif position. As in the case of the rails 84 and 86, the rail 182 is generally in the form of a half cylinder. It will be seen that the rail 1112 is substantially parallel to the rail 1114 and is arranged end to end with respect to the rail 86. It will be understood that the rail 182 is insulated from the rails 84 and 86. The rail 102 is suitably secured to the insulating plate 24-. As shown, the rail 1112 is formed with a laterally projecting tab or lug 184 which is secured to the plate 24 by means of a rivet 166. To prevent the rail 1112 from swinging about the rivet 106, one end of the rail 1112 is formed with an ear or tab 108 which is received in a hole or recess 11% formed in the insulating plate 24.

The contact point on the contactor 58 is adapted to slide between the rails 84 and 102 in the various on positions of the switch. Thus, in all of such positions, the contact point 91) forms a connecting bridge between the rails 84 and 1112.

In addition to the rails 84, 86 and 102, the illustrated contact plate 24 is provided with a plurality of contact points 112, 114 and 116 arranged on opposite sides of the parallel lines of the rails. It will be seen that the contact points 112 and 116 are on the same side of the rail 84 and are along a line parallel to the rail 84. The contact point 114 is on the opposite side of the rails 84 and 1112 and is disposed along a line which also includes the rivets 96 and 106. The contact points 112, 114 and 116 may be in the form of rivets, similar to the rivets 96 and 186. All of the contact points are preferably rounded and generally hemispherical in shape.

The various electrical circuits controlled by the switch may be connected to the rivets or contact points 96, 112, 114, 116 and 186. For this purpose, terminal lugs or prongs 121, 122, 123, 124 and 125 are connected to the respective rivets 96, 106, 112, 114 and 116. The terminal prongs 121-125 are arranged in a regular pattern and are adapted to receive a plug or other connector.

The illustrated contactor 58 has a pair of contact segments or arms 128 and 129 which extend laterally from the main plate portion or body 92 of the contactor. It will be seen that the arms 128 and 129 are formed at the opposite end of the body 92 from the contact point 90. The arm 128 is adapted to engage the contact points 112 and 116 on the insulating contact plate 24. The other arm 129 is adapted to engage the contact point 114. It will be seen that the arms 128 and 129 are offset rearwardly from the body portion 92. In this way, the body portion 92 is prevented from engaging the rails 84, 86 and 102.

In FIG. 6, the movable contactor 58 is shown in broken lines in its OFF position, It will be seen that the contact point 90 engages the rails 84- and 86 but is out of engagement with the rail 182. The arm 129 of the contactor engages the contact or pad 132 which may be an independent contact point, for energizing an independent circuit, but is illustrated as being formed as a dummy contact on the metal tab 94 adjacent the rivet 96. To engage the other arm 128 of the contactor 58, the insulating plate 24 is provided with a contact or pad 134 which is opposite the pad 132. The pad or boss 134 may be formed as an independent contact point, but, as illustrated, is in the form of a semi-perforation punched forwardly from the insulating plate 24. Thus, the illustrated pad 134 is made of insulating material. The eifect of the pads 132 and 134 is to maintain the contactor 58 on an even keel and in its proper position, generally parallel to the insulating plate 24, so as to insure that the pressure due to the spring 60 will be evenly distributed upon the three elements of the contactor. These three elements are the contact point 90 and the arms 128 and 129. In the OFF position of the switch, the contactor 58 is connected electrically to the terminal prong 121, and is not connected to any of the other terminal prongs 122-125.

In the next position of the switch, designated by the initials AC in FIG. 5, the contact point 90 is moved upwardly from the position shown in FIG. 6, so that the contact point engages the lower end of the rail 102 as well as the rail 84. Thus, the contact point 90 establishes a circuit between the rails 84 and 102, so that an electrical connection is provided between the terminal prong 121 and the prong 122. This connection is maintained in all of the other ON positions of the switch, inasmuch as the contact point 90 rides along between the rails 84 and 102. In the AC position of the switch, the arm 129 of the contactor 58 engages the rivet 96, while the arm 128 engages a contact or pad 135, similar to the pad 134. While the pad 135 may be an independent contact, it is shown as an insulating semi-perforation.

In the next position of the switch, designated LOW in FIG. 5, the contact point 90 continues to establish a connection between the rails 84 and 102. The contactor arm 128 engages the contact point 112, while the arm 129 engages a contact or pad 138, similar to the pads or bosses 134 and 135. Thus, the arm 128 establishes a circuit between the terminal prong 121 and the prong 123.

In the fourth or MEDIUM position of the switch, the arm 129 of the contactor engages the contact point 114, while the arm 128 engages still another contact or pad 140, similar to the pads 134, 135 and 138. Thus, a circuit is established between the terminal prong 121 and the prong 124.

In the fifth or HIGH position of the switch, the arm 128 of the contactor engages the contact point 116, while the arm 129 engages the contact point 142, illustrated as being made of metal. Thus, there are four points of metal-to-metal contact between the contactor and the fixed contact structure. Two of such points of contact are between the arms 128 and 129 and the contact points 116 and 142, respectively. The other two points of contact are between the opposite side portions of the contact point 90 and the rails 84 and 102. Nevertheless, the spring pressure is evenly distributed among the four points of contact. While the contact point 142 may be formed independently for connection to an independent circuit, it is illustrated as being formed on a metal plate 144 which is secured to the insulating plate 24 by the contact rivet 114. To prevent the metal plate 144 from rotating about the rivet 114, the plate 144 is formed with a tab 146 which extends rearwardly into an opening of recess 148 in the insulating plate 24.

FIG. 6 illustrates a typical electrical circuit which may be employed in connection with the switch. In this circuit, the switch is employed to control the energization of a clutch solenoid 150 for an air conditioning compressor. When the solenoid is energized, the compressor is driven through a clutch by the engine of the vehicle which carries the air conditioning system. It will be seen that the clutch solenoid 150 is adapted to be connected to the terminal prong 122, and thence to the rivet 106 and the rail 102. The other side of the clutch solenoid 150 may be grounded.

Power is supplied to the switch from a battery 152 or some other suitable source of power. As shown, the positive terminal of the battery is connected to the terminal prong 121 and thence to the rivet 96 and the rails 84 and 86. The negative terminal of the battery is grounded.

Thus, the clutch solenoid 150 is energized in all of the positions of the switch, except the off position. In all of the on positions, the contact point 90 forms a bridge between the rails 84 and 102.

The switch 20 is also employed to control the energization and speed of a motor 154 which drives the blower for the air conditioning system. One side of the motor 154 is connected to the terminal prong 125 and thence to the con-tact point 116. Thus, in the fifth or high position of the switch, the motor 154 is fully energized from the battery 152 by the connection established between the contactor arm 128 and the con-tact point 116. The fact that the contactor arm 129 also energizes the contact point 142 does not affect the operation of the motor 154, because the motor is already fully energized through contactor arm 128 and the contact point 116.

A current limiting resistor 156 is connected between 6 the terminal prongs and 124. Thus, the motor 154 is energized through the resistor 156 when the contactor arm 129 engages the contact point 114 in the fourth or medium position of the switch. The introduction of the resistor 156 into the circuit reduces the speed of the motor 154.

A second resistor 158 is connected between the terminal prongs 124 and 123. When the contactor arm 128 engages the contact point 112 in the second or low position of the switch, the motor 154 is energized through both of the resistors 156 and 158, connected in series, so that the motor is operated at a low speed.

FIGS. 8, 9 and 10 illustrate a slightly modified switch 20a which has only four positions, corresponding to the first four positions of the switch 20. Most of the components of the switch 20a are identicallythe same as the corresponding components of the switch 20, and to that extent the components have been given the same reference characters in FIGS. 8l0 as in FIGS. l7. Thus, it will not be necessary to repeat the description of these components. Only the differences between the switches 20 and 20a need be described in detail.

The switch 20a has a slightly modified operating lever 40a having an outer arm 52:: which differs in shape from the arm 52 but is essentially the same in functions. The lever 40a is swingably mounted on a bracket 42a which is the same in function as the bracket 42, although difie ing to some extent in shape.

In FIG. 8, the four operating positions of the lever 40a are designated off, low, medium and high. These positions correspond to the first four positions of the lever 4a in FIG. 5, although the designations of the positions are somewhat difierent.

The carriage 56 is movable to four positions which are the same as the first four positions of the carriage in the switch of FIGS. 1-7. In the modified switch 20a the carriage 56 is prevented from moving to the fifth position by a pair of stops 170 and 171 which are struck inwardly from the side Walls 28:: and 29a of the casing 22a.

The switch 20a has a slightly modified insulating contact plate 24a on which the arrangement of the various contact elements is simplified to some extent, by the omission of various components. Thus, the contact point 116 and the corresponding terminal prong 125 are omitted. The contact point 142 and the plate 144 are also omitted.

FIG. 10 illustrates a somewhat modified electrical circuit in which the clutch solenoid is omitted. Thus, the switch is employed merely to control the energization and speed of the blower motor 156. In this case, the blower motor 156 is connected between the contact point 114 and the ground. It will be understood that the connection between the contact point 114 and the motor 156 is established by way of the terminal prong 124. The connection of the battery 152 is the same in FIG. 10 as in FIG. 6. However, the resistor 156 is connected between the contact points 114 and 112, by way of the terminal prongs 124 and 123. The second resistor 158 is connected between the contact point 112 and the rivet 106, by way of the prongs 123 and 122.

In the OFF position of the switch 20a, the contactor 53 is in its lowermost position in which the contact point 90 engages the rails 84 and 86. The arms 128 and 129 engage the pads or bosses 134 and 132.

In the second or LOW position of the switch, the contact point 90 forms a bridge between the rails 84 and 102, so that a circuit is established between the battery 152 and the motor 156 through the contactor 58, the rails 84 and 102, the rivet 106, the prong 122 and the resistors 158 and 156. The arms 128 and 129 engage the insulating pad 134 and the rivet 96.

In the third and fourth positions of the switch the contact point 90 continues to form a bridge between the rails 84 and 102. In the third or MEDIUM position, the arm 128 engages the contact point 112, so that the resistor '5" 158 is short-circuited and the motor 154 is energized through the resistor 156.

In the fourth or HIGH position of the switch 20a, the contactor arm 129 engages the contact point 11% and thereby establishes a direct connection to the motor 154, so that it will operate at full speed. In FIG. 10, the contactor 58 is shown in broken lines in its fourth position.

In both of the illustrated switches, the contact point 90 rides freely between the rails 84 and M52, so that two points of contact are maintained between the contact point and the rails. The contactor arms or segments 128 and 129 afford two more points of contact with the fixed contact structure, making four points of contact With the contactor. It will be noted that the contact point 90 and the arms 12% and 129 are arranged in a triangle. Thus, the spring pressure upon the contactor is evenly distributed among the three contact members 98, 128 and 129. The ability of the contact point 9% to ride freely between the rails insures that good contact will be maintained at all four points of contact between the contactor and the fixed contact structure.

It will be understood that the fixed contact rails may be segmented in various ways to meet various circuit requirements. Moreover, the fixed contact points may be varied in number and position so that a wide variety of switching functions may be performed. Similarly, the fixed dummy contacts may be varied in number and position. It will be understood that the shape and position of the contact members on the contactor may also be varied.

The present invention makes it possible to perform various complicated combinations of switching functions in which several circuits are to be selectively energized in various positions of the switch, and in which at least one circuit is to be continuously energized for two or more positions. At the same time, the present invention makes it possible to provide switches having these great capabilities at low cost and with assurance of long life and dependable operation.

Various other modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the present invention, as exemplified in the foregoing description and defined in the following claims.

We claim:

1. In an electrical switch,

the combination comprising a housing having a fixed insulating wall member,

a track comprising first and second fixed elongated substantially parallel conductive contact rails mounted on said insulating wall member within said housing,

at least one of said rails being segmented into a plurality of components,

a conductive contactor movable within said housing and having a first contact member riding in said track between said rails and slidably engaged with said rails to establish a closed circuit therebetween,

actuating means for moving said contactor along said track and Within said housing,

at least two fixed conductive contacts mounted on said insulating wall member within said housing,

said contacts being on opposite sides of said track and spaced laterally from said rails,

and second and third contact members on said contactor and disposed on opposite sides of said track for engagement with said respective contacts,

said contactor having spring means biasing said contactor toward said insulating wall member and against said rails and said contacts,

said first, second and third contact members of said contactor being disposed in a triangular pattern to equalize the spring pressure among said first, second and third contact members.

2. In an electrical switch,

the combination comprising a housing having a fixed insulating wall member,

a track comprising first and second fixed elongated substantially parallel conductive contact rails mounted on said insulating wall member within said housing at least one of said rails being segmented into a plurality of components,

a conductive contactor movable within said housing and having a contact member riding in said track between said rails and slidably engaged with said rails to establish a closed circuit therebetween,

said contactor having spring means biasing said contactor toward said insulating wall member and against said rails,

and actuating means for moving said contactor along said track and within said housing.

3. In an electrical switch,

the combination comprising a housing insulating wall member,

a track comprising first and second fixed elongated substantially parallel conductive contact rails mounted on said insulating Wall member within said housing,

at least one of said rails being segmented into a plurality of components,

a conductive contactor movable within said housing and having a first contact member riding in said track between said rails and slidably engaged with said rails to establish a closed circuit therebetween,

actuating means for moving said contactor along said track and within said housing,

at least one fixed conductive contact mounted on said insulating wall member within said housing on one side of said track and spaced laterally therefrom,

and a second contact member on said contactor and disposed on said one side of said track for engagement with said contact,

said contactor having spring means biasing said contactor toward said insulating wall member and against said rails and said contact.

a. A switch according to claim 1,

in which said first contact member takes the form of a curved contact point projecting from said contactor and slidably engaging both of said rails simultaneously.

5. A switch according to claim 1,

in which each of said contact rails projects from said insulating wall member and is cylindrically curved in cross section.

6. A switch according to claim 1,

in which each of said contact rails projects from said insulating wall member and is cylindrically curved in cross section,

and in which said first contact member takes the form of a curved contact point projecting from said contactor and slidably engaging both of said contact rails simultaneously.

7. A switch according to claim 1,

in which said fixed contacts are in the form of contact points projecting from said insulating wall member,

and in which said insulating wall member is provided with at least one insulating dummy contact boss projecting therefrom on the opposite side of said track from one of said contact points to equalize the spring pressure among said rails, said one contact point and said boss.

8. A switch according to claim l,

in which each of said rails projects from said insulating wall member and is cylindrically curved in cross section,

and in which said first contact member is in the form of a curved convex member projecting from said contactor and slidably engaging both of said rails simultaneously,

and in which said fixed cQIliQCtS are in the form of having a fixed curved contact points projecting from said insulating wall member,

said insulating Wall member being provided with at least one insulating dummy contact boss projecting therefrom and disposed on the opposite side of said track from one of said contact points to equalize the spring pressure among said rails, said one contact point, and said boss.

9. A switch according to claim 2,

in which each of said rails projects from said insulating wall member and is cylindrically curved in cross section,

and in which said contact member takes the form of a curved contact point projecting from said contactor and slidab-ly engaging both of said rails simultaneously.

10. A switch according to claim 3,

in which each of said rails projects from said insulating wall member and is cylindrically curved in cross section,

and in which said first contact member takes the form of a convex member projecting from said contactor and slidably engaging both of said rails simultaneously,

said fixed contact being in the form of a contact point projecting from said insulating wall member.

11. A switch according to claim 1,

in which each of said rails projects from said insulating wall member and is cylindrically curved in cross section,

and in which said first contact member takes the form of a convex member projecting from said contactor and slidably engaging both of said rails simulta neously,

said fixed contacts being in the form of contact points projecting from said insulating wall member.

12. A switch according to claim 2,

in which said contact member takes the form of a curved contact point projecting from said contactor and :slidably engaging both of said rails simultaneously.

13. A switch according to claim 2,

in which each of said rails projects from said insulating wall member and is cylindrically curved in cross section.

14. A switch according to claim 3,

in which said first contact member takes the form of a curved contact point projecting from said contactor and slidably engaging both of said rails simultaneously.

15. A switch according to claim 3,

in which each of said rails projects from said insulating wall member and is cylindrically curved in cross section.

References Cited by the Examiner UNITED STATES PATENTS 2,100,657 11/1937 Edwards 20016 3,030,459 4/1962 Elliott et al 200-16 X 3,097,269 7/ 1963 Campbell 200-168 X 3,125,702 3/1964 Herridge et al 20016 X 3,158,698 11/1964 Campbell ZOO-16 3,174,000 3/1965 Golbeck 20016 X KATHLEEN H. CLAFFY, Primary Examiner.

I. R. SCOTT, Assistant Examiner. 

1. IN AN ELECTRIC SWITCH, THE COMBINATION COMPRISING A HOUSING HAVING A FIXED INSULATING WALL MEMBER, A TRACK COMPRISING FIRST AND SECOND FIXED ELONGATED SUBTANTIALLY PARALLEL CONDUCTIVE RAILS MOUNTED ON SAID INSULATING WALL MEMBER WITHIN SAID HOUSING, AT LEAST ONE OF SAID RAILS BEING SEGMENTED INTO A PLURALITY OF COMPONENTS, A CONDUCTIVE CONTACTOR MOVABLE WITHIN SAID HOUSING AND HAVING A FIRST CONTACT MEMBER RIDING IN SAID TRACK BETWEEN SAID RAILS AND SLIDABLY ENGAGED WITH SAID RAILS TO ESTABLISH A CLOSED CIRCUIT THEREBETWEEN, ACTUATING MEANS FOR MOVING SAID CONTACTOR ALONG SAID TRACK AND WITHIN SAID HOUSING, AT LEAST TWO FIXED CONDUCTIVE CONTACTS MOUNTED ON SAID INSULATING WALL MEMBER WITHIN SAID HOUSING, SAID CONTACTS BEING ON OPPOSITE SIDES OF SAID TRACK AND SPACED LATERALLY FORM SAID RAILS, AND SECOND AND THIRD CONTACT MEMBERS ON SAID CONTACTOR AND DISPOSED ON OPPOSITE SIDES OF SAID TRACK FOR ENGAGEMENT WITH SAID RESPECTIVE CONTACTS, SAID CONTACTOR HAVING SPRING MEANS BIASING SAID CONTACTOR TOWARD SAID INSULATING WALL MEMBER AND AGAINST SAID RAILS AND SAID CONTACTS, SAID FIRST, SECOND AND THIRD CONTACT MEMBERS OF SAID CONTACTOR BEING DISPOSED IN A TRIANGULAR PATTERN TO EQUALIZE THE SPRING PRESSURE AMONG SAID FIRST, SECOND AND THIRD CONTACT MEMBERS. 